RU2353425C1 - Method for preparation of catalyst for dehydration of cyclohexanol into cyclohexanone - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention is related to methods for preparation of catalyst for dehydration of cyclohexanol in cyclohexanone, which contains copper introduced into solid carrier as active component. It is described the method of preparing catalyst for dehydration of cyclohexanol into cyclohexanone by application of active component - copper from water solution of its salt, which is water solution of its ammonia-carbonate complex, and copper is applied on carrier at thermal decomposition of ammonia-carbonate complex at the temperature of 55-350°C.

EFFECT: simplification of method for catalyst preparation for dehydration of cyclohexanol into cyclohexanone with preservation of produced catalyst quality.

2 cl, 1 tbl, 6 ex

Description

The invention relates to methods for preparing a catalyst for the dehydrogenation of cyclohexanol to cyclohexanone containing copper as an active component embedded in a solid carrier.

A known method of preparing a catalyst for dehydrogenation of cyclohexanol to cyclohexanone by applying the active component of copper on a carrier of α-alumina with a BET surface of at least 30 m ² / g The deposition of copper on the carrier with α-alumina with the above characteristics is carried out from aqueous solutions of its salts, mainly nitric acid, acetic acid, sulfate, hydrochloric, by impregnating the carrier or precipitating copper on the carrier in the form of insoluble compounds, mainly carbonates, basic carbonates or hydroxides, as well by dry mixing the catalyst components or currentless copper plating of the carrier followed by calcination (RF Patent No. 2190468, B01J 23/72, 21/04, 37/04, 1997).

Each of the presented methods for applying copper to a carrier has its drawbacks. So, in the case of the impregnation method, there is a limitation on the amount of introduced copper even when the carrier is repeatedly treated with a solution of copper salt, as well as on the formation of contaminated gas emissions, for example, nitrogen oxides, during thermal treatment of the catalyst.

When using the deposition method, an alkaline precipitator is consumed and the catalyst mass needs to be washed from the residual alkali salt formed.

During currentless copper plating (reductive deposition), in order to achieve uniform coating of the support with copper, it is treated with a solution of noble metal compounds (platinum, rhodium, palladium, gold, iridium) to form crystallization centers. In this regard, there are additional costs and unnecessary technological operation. The method has a certain complexity, which consists in pre-applying, as a rule, palladium on a carrier, followed by drying, and then in the deposition of copper on the prepared carrier using caustic soda in the presence of special complexing agents, washing the catalyst mass and heat treating it. In this case, palladium nitrate, caustic soda and pure water for washing are consumed.

Closest to the invention is a method of preparing a catalyst for dehydrogenation of cyclohexanol to cyclohexanone by treating a solid oxide support with an aqueous solution of a copper salt in the presence of a special complexing agent. The deposition of copper on the carrier is carried out by precipitation from an aqueous solution of its nitric acid salt using a precipitating agent - sodium carbonate. In this case, the copper salt solution contains at least one complexing agent in the form of a water-soluble organic polymer, for example acrylamide and / or methacrylamide, or unsaturated ethylene carboxylic acids and their amides, homo- and copolymers of N-vinyl lactam, especially N-vinyl pyrrolidone for coordination binding of copper ions . Of the copper salts, nitrates, acetates, chlorides, sulfates are mainly used to obtain their aqueous solutions, and oxides with a developed specific surface, as a rule silicates, aluminum silicates, aluminum oxides, zirconium and titanium dioxide, or mixtures thereof are used as carriers also zeolites and pumice. The resulting catalyst mass is subjected to heat treatment and granulation (RF Patent No. 2218987, B01J 23/72, 37/03, 31/06, 1998).

The disadvantages of this method include:

- the need for introducing into the reaction system special complexing agents in the form of water-soluble organic polymers;

- the deposition of copper on a carrier by precipitation with sodium carbonate requires both the consumption of a precipitant and the washing of the catalyst mass from alkali salt residues.

This leads to the complexity of the technology and the cost of the catalyst.

The technical result to which the invention is directed is to simplify and reduce the cost of the method of preparation of the catalyst for dehydrogenation of cyclohexanol to cyclohexanone while maintaining the quality of the resulting catalyst.

To achieve a technical result in a method for preparing a catalyst for dehydrogenation of cyclohexanol to cyclohexanone by applying the active component copper from an aqueous solution of its salt to an oxide solid carrier, heat treatment and granulation, according to the invention, an aqueous solution of its ammonia-carbonate complex is used as a solution of copper salt and the deposition of copper on the carrier is carried out by thermal decomposition of its ammonia-carbonate complex at a temperature of 55-350 ° C.

As the oxide solid support, for example, silicon dioxide, magnesium oxide and aluminum oxide, as well as mixtures thereof, are used. In this case, the carrier is a powder or finished granules.

The main distinguishing features of the invention is that a solution of its ammonia-carbonate complex is used as a solution of a copper salt, and copper is deposited on a support by thermal decomposition of the ammonia-carbonate complex at a temperature of 55-350 ° C.

An additional distinguishing feature is that the oxide solid carrier is a powder or finished granules.

The present invention meets the condition of patentability "novelty", since the prior art failed to find a technical solution, the essential features of which would completely coincide with all the features available in the independent claim.

Also, the present invention meets the criteria of the invention of "inventive step", because the prior art could not find a technical solution, the essential features of which ensured the fulfillment of the same technical task to which this invention is directed.

The invention is illustrated by the following examples.

Example 1

In a heated reactor with a stirrer, 200 cm ^{3 of a} solution of an ammonia-carbonate complex of copper containing in g / dm ³ are poured: copper (in terms of CuO) - 100; NH ₃ - 120; СО ₂ - 65. 2.3 g of dry sodium carbonate (soda) are poured into the solution, stirred, and gradually, with a working stirrer, 80 g of silicon dioxide with a specific surface area of 380 m ² / g are poured. If necessary, water is added to the reactor for better mixing. The resulting homogeneous suspension with stirring is heated to 85 ° C and maintained at this temperature until the copper content in the solution is not more than 3-4 g / dm ³ . The resulting catalyst mass is filtered and dried at a temperature of 110-150 ° C to constant weight. The dried mass is ground into powder, mixed with 2% powder graphite and pressed into tablets with a diameter of 5 and a height of 3.5 mm

In the prepared catalyst:

- content, wt.%: copper (in terms of CuO) - 19.3; sodium (in terms of Na ₂ O) - 0.42;

- bulk density, kg / dm ³ - 0.68;

- mechanical strength (destructive force under load on the forming granules), MPa - 4.5.

Example 2

The catalyst is prepared, as in example 1, with the difference that the decomposition of the ammonia-carbonate complex of copper in an aqueous suspension with silicon dioxide with a specific surface area of 380 m ² / g in the decomposition reactor is carried out at a temperature of 55 ° C. Next, the preparation is carried out, as in example 1.

In the prepared catalyst:

- content, wt.%: copper (on CuO) - 19.8; sodium (on N ₂ O) - 0.44.

- bulk density, kg / dm ³ - 0.71;

- mechanical strength, MPa - 4.8.

Example 3

The catalyst is prepared, as in example 1, with the difference that 80 g of powdered large-pore (effective pore diameter of about 10 nm) silica gel with a specific surface of 325 m ² / g is poured into the decomposition reactor.

In the prepared catalyst:

- content, wt.%: copper (in terms of CuO) - 21.2, sodium (in terms of Na ₂ O) -0.5;

- bulk density, kg / dm ³ - 0.8;

- mechanical strength, MPa - 3.8.

Example 4

The catalyst is prepared, as in example 1, with the difference that 80 g of large-pore silica gel in the form of balls (average diameter 3.8 mm), previously moistened with water, is introduced into the decomposition reactor, and stirring is carried out with a stream of nitrogen.

In the prepared catalyst:

- content, wt.%: copper (on CuO) - 18.4; sodium (on Na ₂ O) - 0.5;

- bulk density, kg / dm ³ - 0.65;

- mechanical strength (abrasion) - ≤0.1 wt.%.

Example 5

The catalyst is prepared, as in example 1, with the difference that freshly precipitated hydroxide, hydroxycarbonate or powdered magnesium carbonate in the amount of 80 g in terms of magnesium oxide (MgO) is introduced into the reactor, and the resulting suspension is subjected to heat treatment in a spray dryer at a temperature of 350 ° FROM.

In the prepared catalyst:

- content wt.%: copper (on CuO) - 20.4; sodium (on Na ₂ O) - 0.51;

- bulk density, kg / dm ³ - 0.84;

- mechanical strength, MPa - 3.8.

Example 6

20 kg of silicon dioxide with a specific surface area of 380 m ² / g are loaded into a Z-shaped heated mixer and 200 liters of a solution of ammonia-carbonate copper complex with a concentration of g / dm ³ are gradually added with stirring, g / dm ³ : CuO - 110, NH ₃ - 125; СО ₂ - 72. Upon reaching a homogeneous mass, 60 kg of silicon dioxide and 800 g of sodium carbonate are gradually added to the mixer. The mass in the mixer is heated to 70-80 ° C and kept under stirring until the decomposition of the ammonia-carbonate complex of copper. The resulting paste is dried at a temperature of 110-150 ° C and further cooking, as in example 1.

In the prepared catalyst:

- content, wt.%: copper (on CuO) - 20.1; sodium (on Na ₂ O) - 0.4;

- bulk density, kg / dm ³ - 0.72;

- mechanical strength, MPa - 5.1.

The measurement of the activity of the catalysts was carried out in a flow-type laboratory apparatus at atmospheric pressure and a space velocity of feed of 1.0 h ^-1 .

The activity of the catalysts was evaluated by the total degree of conversion of cyclohexanol to reaction products, and the selectivity by the degree of conversion of cyclohexanol to cyclohexanone in%. The composition of the reaction products was determined by chromatographic method.

The thermal stability of the catalyst was judged by the degree of decrease in activity when testing it at a temperature of 350.

Before starting the test, the catalyst is reduced in a stream of hydrogen at temperatures from 140 to 180 ° C, feed is supplied and preliminary run at 250 ° C is carried out for five hours, after which control samples of dehydrogenation products are taken at temperatures of 220 and 250 ° C. Then the temperature of the reactor was brought to 350 ° C and maintained at the same flow rate of raw materials for 1 hour. After cooling to 250 ° C., control samples are again taken.

The test results are shown in the table.

Table. Defined parameters,% Catalyst, No. of Examples one 2 3 four 5 6 Prototype The degree of conversion at 220 ° C thirty 31 29th thirty 32 29th 29th Selectivity at 220 ° C 99.6 99.6 99.8 99.6 99.8 99.7 99.5 The degree of conversion at 250 ° C 58 57 51 55 54 55 55 Selectivity at 250 ° C 99.6 99,4 99.7 99.5 99.5 99.6 99,4 The degree of conversion at 250 ° C after overheating at 350 ° C 40 42 43 39 44 42 38 Selectivity at 250 ° C after overheating at 350 ° C 99.5 99.5 99.7 99.7 99.5 99.7 99.5

As follows from the data given in the table, in terms of quality parameters (activity and selectivity), the claimed catalyst is not inferior to the prototype.

In addition to maintaining the quality of the catalyst, the proposed method for its preparation also significantly simplifies and reduces the cost of the technology. This is achieved by replacing a solution of copper salt (mainly nitrate or acetate) with the addition of a special complexing agent for coordinating the binding of copper ions to a solution of its ammonia-carbonate complex, which plays a dual role: copper salts and complexing agents. This decision is unexpected. This excludes the use of a precipitating agent (mainly a solution of sodium carbonate) and washing solid precipitation products from the formed sodium salt. The use of a precipitating agent and a special complexing agent and the operation of preparing their solutions are also excluded.

Claims (2)

1. A method of preparing a catalyst for dehydrogenation of cyclohexanol to cyclohexanone by applying the active component - copper from an aqueous solution of its salt to an oxide solid carrier, heat treatment and granulation, characterized in that an aqueous solution of its ammonia-carbonate complex and copper deposition are used as a copper salt on the carrier is carried out during thermal decomposition of the ammonia-carbonate complex at a temperature of 55-350 ° C. 2. The method according to claim 1, characterized in that the oxide solid carrier is a powder or finished granules.